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Clumps of dark matter could be lurking undetected in our galaxy

A hypothetical ‘dark’ force could allow clouds of invisible particles to collapse into small structures

DARK COLLAPSE Dark matter is normally thought to form a spherical halo (illustrated in blue) around galaxies like the Milky Way. Two physicists suggest that dark matter could collapse into more complex structures.

Clumps of dark matter may be sailing through the Milky Way and other galaxies.

Typically thought to form featureless blobs surrounding entire galaxies, dark matter could also collapse into smaller clumps — similar to normal matter condensing into stars and planets — a new study proposes. Thousands of collapsed dark clumps could constitute 10 percent of the Milky Way’s dark matter, researchers from Rutgers University in Piscataway, N.J., report in a paper accepted in Physical Review Letters.

Dark matter is necessary to explain the motions of stars in galaxies. Without an extra source of mass, astronomers can’t explain why stars move at the speeds they do. Such observations suggest that a spherical “halo” of invisible, unidentified massive particles surrounds each galaxy.

But the halo might be only part of the story. “We don

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